Machine tools



Feb. 13, 1962 LEY MACHINE TOOLS 4 Sheets-Sheet 1 Filed Sept. 4, 1958 ii;7 li.

INVENTOR JAMES L. HENSLEY ATTORNEYS 1962 J. HENSLEY 3020'679 MACHINETOOLS Filed Sept. 4, 1958 4 Sheets-Sheet 2 INVENTOR J4MES L. HENSLEYATTORNEYS Feb. 13, 1962 J. L. HENSLEY MACHINE TOOLS 4 Sheets-Sheet 4Filed Sept. 4, 1958 m H I I I I I I I I I I I I I I I I I 0 H INVENTORJAMES L. HE'NSLEY ATTORNEYS 3,020,679 MACHINE TOOLS James L. Hensley,Clinton, Team, assignor to Ty-Sa-Man Machine Company, Knoxville, Tenn.,a corporation of Tennessee Filed Sept. 4, 1958, Ser. No. 759,076 8Claims. (Cl. 51-34) This invention relates to improvements in machinetools, and more particularly to improved means for mounting and drivingthe end portions of the tool-carrying structures of machine tools suchas grinders, saws, and the like.

Although the invention may be utilized advantageously in many difierenttypes of machines, it will be convenient to refer specifically to theapplication of the invention in a grinding machine of the type disclosedin Palmer Patent 2,807,123, granted September 24, 1957. The invention isparticularly advantageous in such grinding machines, and, having gainedan understanding of this embodiment, persons skilled in the art willperceive readily the manner in which the invention may be applied toother types of machines.

The grinding machine disclosed in said Palmer patent includes anelongated bed for supporting steel billets or other large objects to beground. A rotating grinding wheel is disposed above the bed and is somounted that it may be moved vertically, transversely with respect tothe bed, or longitudinally of the bed. As a result, the wheel may bebrought into contact with all or any desired portion of the uppersurface of the object being ground. These several movements areindependent, in the sense that a separate mechanism is employed for eachof them. The rotating Wheel is mounted for vertical movements withrespect to an overhead carriage; the carriage is mounted upon atransversely extending bridge or crosshead for movements back and forthacross the bed; and the bridge is mounted upon longitudinally extendingrails on opposite sides of the bed for movements longitudinally of thebed. The present invention is concerned primarily with the means fordriving the bridge back and forth along these rails.

According to the disclosure of the Palmer patent, the bridge carriessets of flanged rollers or wheels which cooperate with the rails in muchthe same manner as the wheels of a railroad car cooperate with thetracks. The drive for the bridge was in the form of a rack and pinionmechanism. Pinions were fixed to the end portions of a power drivencross shaft extending through the bridge and entirely across themachine. Cooperating with these pinions were long stationary racks fixedin position with respect to the rails. Upon rotation of the cross shaft,the pinions would move along the racks to drive the bridge along therails.

Another type of drive which has been employed heretofore is of the screwtype. In this type of drive, rotatable nuts mounted upon each end of thebridge coact with long screw elements extending along each of the rails.As will be evident, such constructions are very similar in operation tothe rack and pinion type disclosed in the Palmer patent.

One of the basic ideas underlying both of these types of drives is thatpositive control should be exercised over the movements of the endportions of the bridge. If the bridge is initially aligned at rightangles to the rails, and it the end portions of the bridge always movetogether along the rails, the bridge will remain in alignment andbinding will be prevented. Although this theory obviously is a soundone, the structures proposed heretofore have made it difficult andexpensive to carry out in practice. The physical characteristics of longscrews and long racks States Patent Free 3,020,679 Patented Feb. 13,1962 are such that a number of difficulties are inherent in bridgedrives employing such elements.

"Moreover, these prior structures have proved to be rather sensitive tothe shock loads resulting from sudden reversals in the direction oflongitudinal movement of the bridge along the rails. In a'rack andpinion drive, for example, the entire load often must be borne by asingle pair of meshing teeth at each end of the bridge, and shearing ofthe teeth becomes a problem.

It is an object of this invention to provide improved bridge drivingmeans which will be inexpensive and durable and which will be easy toinstall and to repair.

Another object of the invention is to provide a structure of thischaracter which can be fabricated from parts which are readily availablein the variety of sizes required for machines of different lengths, soas to obviate the difliculties encountered heretofore in obtaining longracks or long screws.

Another object of the invention is to provide bridge driving means of aconstruction such that it may be adjusted easily and quickly tocompensate for wear between the relatively movable parts and to assureproper alignment oi'the bridge transversely of the machine.

Still another object of the invention is to improve the resistance ofbridge driving structures to the shock loads which result from reversalsin the direction of bridge movement.

The foregoing objects may be accomplished, according to one embodimentof the invention, by so constructing a machine of the type having a pairof elongated rails and a bridge movable along such rails that the bridgeis driven back and forth along the rails by means of a sprocket andchain mechanism. The drive for the bridge includes a sprocket wheelmounted upon each end portion of a power driven cross shaft whichextends from one end of the bridge to the other, and a pair ofstationary chains in position to cooperate with the sprocket wheels.Each chain has its end portions fixed with respect to one of the railsby means which will permit adjustment of the longitudinal position ofthe chain. An intermediate portion of each chain is looped about one ofthe sprocket wheels and held in firm engagement therewith by idlerwheels on the bridge. These idler wheels also may be adjusted to assureproper contact between the chains and the sprocket wheels at all times.

Such a drive may be applied easily to machines of vary ing sizes andtypes. Chains are widely available on a commercial basis, and thecorrect length required for a particular installation may be obtained bythe simple expedient of adding or removing links. The same expedient maybe employed when it becomes necessary to make adjustments to compensatefor wear on the parts.

Another outstanding advantage of the system is the ease with which thebridge may be kept in proper alignment transversely of the rails of themachine; If at any time, either during installation or after a period ofuse, the bridge were to become skewed slightly with respect to therails,'it could be straightened out very quickly by adjusting the endfittings on the chains so as to produce a slight longitudinal shiftingmovement of the chains relative to each other. No comparable result'hasbeen attainable as a practical matter in machines having the types ofdrives used heretofore. i Q

The chain drive also results in a new force distribution pattern whichis especially desirable in connection with the large loads caused bysudden reversals in the d rection of bridge movement." Each chaincooperates with a substantial portion of the periphery of the sprocketwheel associated therewith, so that the unit load transmitted to theindividual linksiis substantially less than that ordinarily imposed uponthe teeth of a rack under like conditions. Moreover, the chain as aWhole is loaded in tension to provide a long ength of material which mayundergo elastic deformation if necessary to prevent the development offorce concentrations of sufficient magnitude to endanger the structuralintegrity of the individual links.

A better understanding of the construction of this invention and itsmany advantages will be gained from a consideration of the followingdetailed description of the embodiment illustrated in the accompanyingdrawings in which:

FIG. 1 is a plan view, with certain parts broken away, of a grindingmachine embodying the present invention;

FIG. 2 is an end view of the bridge of the grinding machine and shows aportion of one of the rails for supporting the bridge;

FIG. 3 is a transverse cross sectional view taken along the line 3-3 inFIG. 2;

FIG. 4 is a transverse cross sectional view of one end portion of thebridge as viewed along the line 4-4 in FIG. 2;

FIG. 5 is a detail vertical cross sectional view taken along the line5-5 in FIG. 4;

FIG. 6 is a transverse cross sectional view of one end portion of thebridge and is taken along the line 66 in FIG. 2; and

FIG. 7 is a partial perspective view showing the means employed foranchoring the end portions of the chains of the drive mechanism.

Referring initially to FIG. 1, it will be observed that the illustratedmachine is of the same general type as that disclosed in Palmer PatentNo. 2,807,123. A carriage structure designated generally by the numeral10 serves to support a grinding wheel in position for treating thesurfaces of objects, such as steel billets, disposed therebeneath. Thecarriage 16 is mounted for reciprocating movements back and forth acrossa beam 12 which forms a part of a bridge structure designated generallyby the numeral 14. The end portions 16 and 18 of the bridge 14 aremounted upon and driven back and forth along elongated rails 20. in atypical installation, the lengths of the rails may be fifteen feet orlonger, so that the total area which can be effectively treated by agrinding wheel supported on the carriage it) is quite substantial.

The manner in which the end portions 16 and 18 of the bridge 14 aresupported upon the rails 20 is clearly illustrated in FIGS. 2, 3, 4 and6 of the drawings. The end portions 16 and 18 include rigid frame units22 and 24 respectively, which may be of any suitable configurations. Thetrack-engaging components carried by each of the frameworks 22 and 24are identical, and a description of those associated with the framework22 will be sufiicient to enable persons skilled in the art to understandthe structure.

The inner and outer side walls of the framework 22 have mounted thereonbearings 26 for rotatably sup porting transversely extending shaftmembers 23 located adjacent each end of the framework 22. Each of theshafts 23, in turn, carries a wheel 30 for engaging the track portion ofthe rail 20 associated with the end portion 16 of the bridge 14. Therail 20 is made up of a wear plate 32 welded or otherwise rigidlysecured to the upper surface of a track 34 in position to be contactedby the wheels 30, and an I-beam 36 for supporting the track member 34.Of course, it will be understood that the I-beam 36 is mounted upon somesuitable frame so that it will be located at the proper elevation withrespect to the bed of the machine.

The framework 22 also has mounted thereon a pair of rollers 38 and 40for engaging Wear plates 41 rigidly secured to the sides of the trackmember 34 to hold the framework 22 securely in position upon the rail26. In order that the distance between the rollers 38 and 40 may beadjusted so as to compensate for wear between the parts, each of theserollers is adjustably mounted upon the framework 22 by means bestillustrated in FIGS. 4 and 5. The inner and outer side walls of theframework 22 have secured thereto sleeves 42 which receive vertical rods44. Although the fit between each rod 44 and its sleeve 42 should besuch as to permit rotation of the rod 44 relative to the sleeve 42, therod 44 normally will be held stationary in a predetermined angularposition by a set screw 46 mounted upon the sleeve 42 and engaging thesurface of the rod 44. Vertical movement of each rod 44 in a downwarddirection is prevented by a collar 48 suitably secured to the upper endportion of the rod 44 in position to bear against the upper end of thesleeve $2. Below the sleeve 42, the rod 44 is provided with eccentricend portion 50 upon which bearings 52 for the rollers 38 and 40 may bemounted.

As will be evident, adjustment of the axes of the rollers 38 and 40 maybe accomplished easily by merely loosening the set screws 4-6 androtating the rods 44 so as to shift the eccentric portions 59 relativeto each other. Therefore, the effort required to maintain the properbearing relationship between the peripheries of the rollers 38 and 40and the wear plates 41 on the side walls of the track 34 is minimized,and satisfactory guiding of the end portions of the bridge 14 along therails 20 is assured.

A motor 54- for driving the bridge 14 back and forth along the rails 29has been illustrated diagrammatically in FIG. l, but has been omittedfrom the other views in the interest of clarity. The motor 54 is mountedupon the upper end of a conventional gear box 56 carried by theframework 22 of the end portion 16 of the bridge 14, and its outputshaft 58 carries a pulley 60 for driving a belt 62. As shown clearly inFIG. 2, the belt 62 passes around a pulley 64 on an input shaft 66 forsupplying power to the gear box 56.

The gear box 56 operates in the usual manner and serves as a speedreducing mechanism. Its output shaft 68 has mounted thereon a sprocketwheel 7 0 for driving a roller chain 72 which passes around a sprocketwheel 74 (FIG. 3) fixed to a cross shaft 76. The cross shaft 76 extendsentirely across the machine and is mounted for rotation about ahorizontal axis by suitable bearings 78 fixed to the frameworks 22 and24 at the end portions 16 and 18 of the bridge 14. In the illustratedconstruction, the transverse beam 12 of the bridge 14 is hollow, and thecentral portion of the cross shaft 76 is disposed within the beam 12.However, the relative locations of the beam 12 and the central portionof the cross shaft 76 may be varied if desired.

Each end portion of the cross shaft 76 has fixed thereto a drivesprocket 30 for moving the bridge 14 back and forth along the rails 20upon rotation of the cross shaft 76. In order to accomplish this result,each sprocket 80 engages an intermediate portion of a long roller chain82, the ends of which are held stationary with respect to the rails 20by means which will be described in greater detail below.

Each of the chains 82 is guided around a substantial portion of itssprocket wheel 80 by means of a pair of chain idler wheels 84 havingsmooth peripherial surfaces 86 for contacting the chain 82. The absenceof sprocket teeth on the chain idler wheels 84 permits adjustment of thewheels 84 with respect to the chains 32 without regard to the spacing ofthe transverse roller members in the chains 82.

Each pair of the chain idler wheels 84 is supported by a bracket member88 secured by bolts 90 or other suitable means to an angle member 22welded to the outer side wall of one of the framework units 22 and 24.Referring to the lower left portion of FIG. 3, it will be observed thateach chain idler Wheel 84 is mounted upon bearings 94 held in place onan eccentric portion 96 of a stud member 98 carried by the bracket 88. Acover plate receives the outer end portions of the stud elements 98 foreach pair of idler wheels 84 and is clamped in position by nuts 102threadedly engaging the stud elements 98. In order to adjust theposition of a chain idler wheel, it is necessary to turn the nut 102 onits mounting stud 98 slightly so as to free the cover plate 100 fromclamping engagement with the eccentric portion 96 of the stud element98. Then the stud element 98 may be rotated slightly about its axis tochange the position of its eccentric portion 96. The parts then may besecured in their adjusted positions by tightening the nut 102.

As each chain 82 passes outwardly around the idler wheels 84, it comesinto contact with a supporting member fixed to brackets 106 mounted uponthe I-beam member 36 of the longitudinal rail 20. These guide members104 preferably extend along substantially the full lengths of the rails20 to support the chains 82 so as to prevent any tendency for the chains82 to sag under their own weight. As a result, tightening of the chains82 to obviate the existence of slack is materially simplified.

FIG. 7 illustrates the manner in which the extreme end portions of thechains 82 are connected to the rails 20. The end of each rail 20 hasfixed thereto a laterally extending member 108 which extends intoalignment with the axis of the adjacent chain 82. The endmost link 110of the chain 82 is pivotally connected to an end of a bolt 112, whichpasses through an opening in the bracket member 108 and is adjustablysecured thereto by nuts 114 engaging opposite faces of the member 108.When it is desired to adjust the chain 82, the nuts 114 are manipulatedso as to move the endmost link 110 of the chain 82 toward or away fromthe end member 108, as desired.

During initial assembly of the apparatus, the chains 82 are brought intooperative position with respect to their drive sprockets 80 before theends of the chains 82 are fixed to therails 20. In this connection, itwill be observed that When a chain 82 is brought into contact with asprocket wheel 80, the chain 82 will be fixed relative to the bridge 14so long as the cross shaft 76 is held against rotation. Therefore,bodily movements of the chains 82 along the rails 20 will result inmovements of the end portions of the bridge 14. These bodily movementsof the chains 82 may be controlled closely by the bolts 112 which serveto connect the ends of the chains 82 to the rails 20. If the bridge 14should be skewed slightly with respect to the rails 20, it may bebrought into proper alignment by adjustment of one chain 82 relative tothe other chain 82 so as to swing the ends of the bridge 14 into therequired positions.

After a machine has been in operation for some time, it frequently willbe found that further adjustments in the alignment of the bridge aredesirable. These also may be accommodated in the manner described above.It is such a simple matter to adjust the alignment of the bridge 14 bymanipulating the appropriate bolts 112 that the operators of themachines will have no hesitancy about undertaking such adjustmentswhenever necessary. Moreover, it will be observed that the time requiredfor an adjustment of this character is exceedingly short so thatproduction operations need not be suspended for prolonged periods oftime.

Maintenance is further simplified by the facility with whichcompensations for wear between the teeth of the sprocket wheels 80 andthe links of the chains 82 may be effected. The adjustable idler wheels84 and the bolts 112 may be moved sufficiently to take care of much ofthe wear. Then, when the centrally located links of the chains 82 wearout, it is not difficult to replace these links so as to restore thechains 82 to their original condition.

Although a single embodiment of the invention has been illustrated anddescribed in detail, various changes and modifications will be apparentto persons skilled in the art. It is intended, therefore, that theforegoing description be considered as exemplary only, and that thescope of the invention be ascertained from the following claims.

I claim:

1. In apparatus of the type having frame means including a pair ofspaced apart parallel rails and a structure extending across the spacebetween said rails and being mounted on said rails for movement alongsaid rails, the improvement which comprises a first drive assemblydisposed adjacent to one of said rails; said drive assembly including asprocket wheel mounted on said structure for rotation about an axisextending transversely of said rails, a chain disposed in the plane ofsaid sprocket wheel and being looped about a portion of the periphery ofsaid sprocket wheel, means fixing the end portions of said chain to saidframe means at points located upon a line in said plane, a pair of guidewheels having smooth peripheries for contacting said chain as it passesfrom said line to the periphery of said sprocket wheel, and adjustablemeans mounting said guide wheels on said structure for free rotation inthe plane of said sprocket wheel about axes which may be shiftedrelative to the. axis of said sprocket wheel to adjust the position ofsaid chain; a second drive assembly like said first drive assemblydisposed adjacent to the other of said rails; and means for rotating thesprocket wheels of said assemblies simultaneously to move said sprocketwheels along said chains and thereby cause said structure to move alongsaid rails.

2. In apparatus of the type having frame means including a pair ofspaced apart parallel rails and a structure extending across the spacesbetween said rails and being mounted on 'said rails for movement alongsaid rails, the improvement which comprises a first drive assemblydisposed adjacent to one of said rails; said drive assembly including asprocket wheel mounted on said structure for rotation about an axisextending transversely of said rails, a chain disposed in the plane ofsaid sprocket wheel and being looped about a portion of the periphery ofsaid sprocket wheel, adjustable means fixing the end portions of saidchain to said frame means'at points located upon a line in said planeand permitting lengthwise adjustment of said end portions, a pair ofguide wheels having smooth peripheries for contacting said chain as itpasses from said line to the periphery of said sprocket wheel, andadjustable means mounting each of said guide Wheels on said structure,each of said last-mentioned adjustable means including a shaft carriedby said structure for rotational adjustment thereon and having aneccentric portion and bearing means mounting a guide wheel on theeccentric portion for free rotation, whereby the axes of said guidewheels may be shifted relative to the axis of said sprocket wheel toadjust the position of said chain; a second drive assembly like saidfirst drive assembly disposed adjacent to the other of said rails; andmeans for rotating the sprocket wheels of said assemblies simultaneouslyto move said sprocket wheels along said chains and thereby cause saidstructure to move along said rails.

3. In apparatus of the type having frame means including a pair ofspaced apart, horizontally extending parallel rails, and a structureextending across the space between said rails and being mounted on saidrails for movement along said rails, the improvement which comprises afirst drive assembly disposed adjacent to one of said rails; said driveassembly including a sprocket wheel mounted on said structure forrotation about an axis extending transversely of said rails, a chaindisposed in the plane of said sprocket wheel and being looped about aportion of the periphery of said sprocket wheel, means fixing the endportions of said chain to said frame means at points located upon ahorizontal line in said plane below said sprocket wheel, a pair of chainguide wheels having smooth peripheries for guiding portions of saidchain between said line and said sprocket wheel, and adjustable meansmounting said guide wheels on said structure adjacent said line for freerotation in the plane of said sprocket wheel about axes which may beshifted relative to said line to adjust said chain, and an elongatedsupport fixed to said frame means and having an upper face positionedimmediately below-said line for supporting the portion of said chainextending along said line; a second drive assembly like said first driveassembly disposed adjacent to the other of said rails; and means forrotating the sprocket wheels of said assemblies simultaneously to movesaid wheels along said chains and thereby cause said structure to movealong said rails.

4. In apparatus of the type having frame means including a pair ofspaced apart parallel rails and a structure extending across the spacebetween said rails and being mounted on said rails for movement alongsaid rails, the improvement which comprises a first drive assemblydisposed adjacent to one of said rails; said drive assembly including asprocket wheel mounted on said structure for rotation about an axisextending transversely of said rails, a chain disposed in the plane ofsaid sprocket wheel and being looped about a portion of the periphery ofsaid sprocket wheel, means fixing the end portions of said chain to saidframe means at points located upon a line in said plane, a pair of guidewheels having smooth peripheries for contacting said chain as it passesfrom said line to the periphery of said sprocket wheel, and meansmounting said guide wheels on said structure for free rotation in theplane of said sprocket wheel; a second drive assembly like said firstdrive assembly disposed adjacent to the other of said rails; and meansfor rotating the sprocket wheels of said assemblies simultaneously tomove said sprocket wheels along said chains and thereby cause saidstructure to move along said rails.

5. In apparatus of the type having frame means including a pair ofspaced apart parallel rails and a structure extending across the spacesbetween said rails and being mounted on said rails for movement alongsaid rails, the improvement which comprises a first drive assemblydisposed adjacent to one of said rails; said drive assembly including asprocket wheel mounted on said structure for rotation about an axisextending transversely of said rails, a chain disposed in the plane ofsaid sprocket wheel and being looped about a portion of the periphery ofsaid sprocket wheel, means fixing the end portions of said chain to saidframe means at points located upon a line in said plane, a pair of guidewheels having smooth peripheries for contacting said chain as it passesfrom said line to the periphery of said sprocket wheel, and meansmounting each of said guide wheels on said structure, each of saidlast-mentioned means including a shaft carried by said structure forrotational adjustment thereon and having an eccentric portion andbearing means mounting a guide wheel on the eccentric portion for freerotation, whereby the axes of said guide wheels may be shifted relativeto the axis of said sprocket wheel to adjust the position of said chain,a second drive assembly like said first drive assembly disposed adjacentto the other of said rails; and means for rotating the sprocket wheelsof said assemblies simultaneously to move said sprocket wheels alongsaid chains and thereby cause said structure to move along said rails.

6. In a machine tool having a pair of spaced part parallel rails and astructure extending across the space between the rails and being mountedon the rails for movement therealong, the combination therewith, ofdrive means for moving the structure along the rails, said drive meanscomprising a sprocket wheel mounted on the structure for rotation aboutan axis extending transversely of said rails, a chain extendinglengthwise of one of the rails and having opposite end portions fixedrelative to said rail, said chain having a looped portion thereofintermediate said ends extending over the sprocket, and a pair of guidewheels having smooth peripheries in guiding relation to the chain onopposite sides of the looped portion.

7. In a machine tool having a pair of spaced apart parallel rails and astructure extending across the space between the rails and being mountedon the rails for movement therealong, the combination therewith, ofdrive means for moving the structure along the rails, said drive meanscomprising a sprocket wheel mounted on the structure for rotation aboutan axis extending transversely of said rails, a chain extendinglengthwise of one of the rails and having opposite end portions fixedrelative to said rail, said chain having a looped portion thereofintermediate said ends extending over the sprocket, and a pair of guidewheels in guiding relation with the chain on opposite sides of thelooped portion and with the sides of the looped portion tangent to theguide wheels spaced apart a distance no greater than the diameter of thesprocket wheel.

8. In a machine tool having a pair of spaced apart parallel rails and astructure extending across the space between the rails and being mountedon the rails for movement therealong, the combination therewith, ofdrive means for moving the structure along the rails, said drive meanscomprising a sprocket wheel mounted on the structure for rotation aboutan axis extending transversely of said rails, a chain extendinglengthwise of one of the rails and having opposite end portions fixedrelative to said rail, said chain having a looped portion thereofintermediate said ends extending over the sprocket, and a pair of guidewheels in guiding relation with the chain on opposite sides of thelooped portion, said guide wheels having their peripheries closer to theperiphery of the sprocket wheel than the diameter of the wheels.

References Cited in the file of this patent UNITED STATES PATENTS1,655,578 Stebbins Jan. 10, 1928 2,128,023 Specht et a1 Aug. 23, 19382,427,135 Guier Sept. 9, 1947 2,807,123 Palmer Sept. 24, 1957 FOREIGNPATENTS 9,512 Germany Nov. 26, 1879

